Harrison was one of three junior-college transfers to sign a letter of intent with the Ducks over the winter. He’s a three-star player from Contra Costa (Calif.) College who has three years in which to play two at Oregon.

The Ducks return one of two starters at cornerback, Ifo Ekpre-Olomu, who announced this week he would remain in school rather than enter this year’s NFL draft. Senior Dior Mathis, senior Troy Hill – who was suspended for the final two games of last season – and redshirt freshman Chris Seisay are among the returning candidates to replace Mitchell.

Ragin, 6-foot-3 and 225 pounds, is a former three-star recruit and second-team all-state linebacker at Wilsonville High. He had one sack among his two tackles in eight games as a true freshman for Cal in 2013, having played primarily on special teams.

Typically, rules would require that Ragin pay his own way after transferring within the conference, but the Pac-12 granted a request to allow Ragin a scholarship immediately. It’s expected he’ll sit out the 2014 season as a transfer before being eligible for the Ducks, whose pipeline of young linebackers now includes Ragin along with Tyrell Robinson, Danny Mattingly, Oshay Dunmore and Torrodney Prevot.